DIVERSITY  OF 
.  ILLINOIS 

; 


NQN  CIRCULATING 

CHECK  FOR  UNBOUND 
CIRCULATING  COPY 


UNIVERSITY  OF  ILLINOIS 

Agricultural  Experiment  Station 


BULLETIN  No.  264 


WHEAT   ROSETTE  AND 
ITS   CONTROL 

IN    COOPERATION    WITH   OFFICE   OF    CEREAL    INVESTIGATIONS 
BUREAU  OF   PLANT   INDUSTRY,  U.    S.   DEPARTMENT  OF  AGRICULTURE 

BY  H.  H.  McKiNNEY,  R.  W.  WEBB, 
AND  G.  H.  DUNCAN 


URBANA,  ILLINOIS,  APRIL,  1925 


SUMMARY 

Rosette  is  a  disease  of  unknown  cause  occurring  on  a  few  varieties  of  winter 
wheat.  Altho  in  many  ways  it  behaves  as  a  definite  disease  restricted  to  these  varieties, 
there  are  indications  that  it  may  constitute  only  a  very  severe  phase  of  what  appears 
to  be  a  mosaic  disease  occurring  on  a  rather  large  number  of  winter  wheats. 

Rosette  was  first  observed  in  1919  near  Granite  City,  Madison  county,  Illinois. 
Later  it  was  found  in  Sangamon,  Mason,  and  Logan  counties,  Illinois,  and  in 
LaPorte,  Porter,  and  Tippecanoe  counties,  Indiana.  When  the  disease  was  first  observed 
it  was  thought  to  be  the  take-all  disease,  but  later  studies  show  that  it  is  distinct  from 
take-all. 

Altho  rosette  has  caused  great  loss  in  infested  fields,  it  has  never  been  of  general 
economic  importance  because  it  is  controlled  by  the  use  of  resistant  varieties.  The 
disease  appears  in  the  early  spring,  producing  spots  in  the  infested  fields  where  it 
causes  the  plants  to  become  dwarfed.  Many  of  the  older  leaves  of  infected  plants  turn 
a.  blue-green  color,  whereas  the  younger  growing  leaves  develop  a  typical  mosaic  mottling 
at  some  time  in  their  development. 

No  fungus  is  consistently  associated  with  the  vital  tissues  of  diseased  plants  in 
the  early  spring.  Helminthosporium  sativum  and  other  fungi  occur  superficially  on  a 
few  of  the  plants  and  later  in  the  spring  a  secondary  rot  sets  in. 

Microscopic  examinations  show  the  presence  of  necrotic  areas,  or  lesions,  in  the 
interior  of  the  tissues  of  the  crown  region  of  diseased  plants  and  a  characteristic 
inclusion  body  is  also  present  in  many  of  the  cells.  These  cell  inclusions  are  also 
associated  with  plants  of  varieties  which  are  affected  with  a  mosaic  mottling  of  the 
leaves,  but  which  never  develop  the  rosette  symptoms.  Cell  inclusions  have  never  been 
found  in  the  plants  of  any  variety  growing  in  soil  known  to  be  free  from  the  leaf 
mottling  causal  agent. 

These  cell  inclusions  are  similar  to  certain  of  those  associated  with  the  known 
virus  disease  of  other  plants,  and  they  also  are  similar  to  some  which  are  found  in  asso- 
ciation with  certain  of  the  virus  diseases  of  man  and  the  lower  animals.  Their  exact 
nature  is  not  known. 

The  cause  of  rosette  has  been  attributed  by  some  workers  to  Helminthosporium 
sativum;  however,  the  experimental  evidence  presented  in  this  paper  does  not  favor  this 
conclusion.  At  the  present  time  there  are  indications  that  it  may  be  caused  by  some 
unusual  type  of  virus.  The  rosette  and  leaf  mottling  conditions  are  soil-borne.  Rosette 
and  mosaic  leaf  mottling  developed  in  great  abundance  in  air-dried  infested  field  soil 
which  had  been  stored  under  greenhouse  conditions  for  three  years. 

The  disease  is  controlled  experimentally  by  treating  infested  soil  with  an  .8-percent 
solution  of  formaldehyde  and  by  disinfecting  the  soil  with  steam.  It  is  completely  con- 
trolled in  the  field  by  the  use  of  resistant  or  immune  varieties;  those  best  adapted  to 
the  infested  areas  include:  Blackhull,  Fulcaster,  Fultz,  Gipsy,  Gladden,  Kanred.  Mam- 
moth Red,  Michikoff,  Red  May,  Red  Rock,  Red  Russian,  Red  Wave,  and  Turkey. 
The  list  of  most  susceptible  varieties  includes:  "Brunswick,"  Fultz  (Kentucky  selec- 
tion), Harvest  Queen  (white  chaffed  Red  Cross),  Illini  Chief,  Missouri  Bluestem, 
Nigger,  and  Penquite.  Many  of  the  varieties  which  are  resistant  to  rosette  are  highly 
susceptible  to  the  mosaic  leaf  mottling.  In  but  few  cases,  however,  does  this  condition 
seem  to  be  of  economic  importance. 


WHEAT    ROSETTE  AND 
ITS   CONTROL 

BY  H.  H.  MCKINNEY,  R.  W.  WEBB,  AND  G.  H.  DUNCAN' 

The  rosette  disease  of  wheat  was  reported  from  Madison  county, 
Illinois,  in  April,  1919.  Later,  it  was  found  in  other  counties  in  the 
state  and  in  several  counties  in  Indiana.  At  that  time  the  disease  was 
thought  to  be  the  take-all  disease  which  occurs  in  Australia  and  in 
Europe.  However,  investigations  which  have  been  reported6  show  that 
the  rosette  disease  differs  from  take-all  in  plant  symptoms  and  also  in 
its  varietal  and  host  ranges.  Furthermore,  Ophiobolus  graminis,  the 
fungus  which  causes  take-all,  has  never  been  found  associated  with  the 
rosette  disease. 

Altho  in  many  ways  rosette  behaves  as  a  definite  disease  restricted 
to  a  limited  number  of  varieties  of  winter  wheat,  this  interpretation 
should  not  be  definitely  accepted  at  this  time.  It  was  pointed  out  in  a 
previous  publication10  that  there  is  a  considerable  amount  of  evidence 
which  indicates  that  the  rosette  disease  may  constitute  a  severe  expres- 
sion of  a  mosaic  disease. 

Soon  after  the  discovery  of  the  rosette  disease,  cooperative  investi- 
gations of  the  malady  were  started  by  the  Office  of  Cereal  Investiga- 
tions, United  States  Department  of  Agriculture,  and  the  Illinois, 
Indiana,  and  Wisconsin  Agricultural  Experiment  Stations.  It  is  the 
purpose  of  the  present  bulletin  to  summarize  the  principal  results  of 
these  investigations. 

OCCURRENCE  OF  ROSETTE 

The  rosette  disease  has  been  found  in  four  counties  in  Illinois  and 
in  three  counties  in  Indiana,  as  shown  in  Table  1.  It  is  very  likely 
that  the  infested  area  is  greater  than  that  shown  in  the  table,  but  as 
most  wheat  varieties  commonly  grown  are  not  susceptible  to  rosette, 
additional  areas  cannot  readily  be  detected. 


•H.  H.  McKinney  and  R.  W.  Webb,  Associate  Pathologists,  Office  of  Cereal 
Investigations,  U.  S.  Department  of  Agriculture;  G.  H.  Dungan,  Associate  in  Crop 
Production,  Illinois  Agricultural  Experiment  Station. 

The  writers  wish  to  express  their  appreciation  to  Dr.  W.  L.  Burlison  and  Dr. 
A.  G.  Johnson  for  helpful  criticisms  during  the  preparation  of  the  manuscript;  to 
Dr.  C.  E.  Leighty,  who  supplied  most  of  the  seed  used  and  furnished  information  in 
regard  to  characteristics  and  adaptation  of  wheat  varieties;  to  Mr.  J.  B.  Kendrick  for 
cooperation  in  the  control  experiments;  to  the  Board  of  Education  of  Granite  City, 
Illinois,  for  providing  laboratory  facilities;  and  to  Mr.  Louis  Soechtig,  on  whose  land 
the  experiments  were  conducted. 

275 


276  BULLETIN  No.  264  [April, 

TABLE  1. — DISTRIBUTION  OF  THE  ROSETTE  DISEASE  IN  THE  UNITED  STATES 


State 

County 

Number  of 
infested  fields 
found 

Approximate 
acreage  of  infested 
fields 

Illinois  .               ... 

Madison  

27 

670 

Mason  

48 

1310 

Sangamon  

2 

380 

Logan  

1 

20 

Indiana   

LaPorte  

7 

213 

Porter  

6 

120 

Tippecanoe  

1 

5 

The  distribution  of  the  mosaic  mottling  independent  of  rosette  has 
not  been  determined.  Rosette  is  not  known  to  occur  in  other  countries 
and  consequently  nothing  is  known  of  the  origin  of  the  malady.  When 


FIG.  1. — SPOT  IN  A  FIELD  OF  HARVEST  QUEEN  (SALZER'S  PRIZETAKER,  RED 

CROSS)  CAUSED  BY  THE  ROSETTE  DISEASE 

The  diseased  plants  within  the  spot  are  considerably  dwarfed  in  contrast 
with  surrounding  healthy  ones. 

more  information  has  been  obtained  on  the  cause  of  the  disease  and  its 
relation  to  the  mosaic  leaf  mottling,  more  light  may  be  thrown  on  its 
distribution  and  origin. 

LOSSES  CAUSED  BY  ROSETTE 

Altho  the  rosette  disease  appears  to  be  confined  to  relatively  small 
areas,  its  importance  should  not  be  underestimated.  When  conditions 
are  favorable  the  disease  has  caused  as  high  as  40  percent  actual  loss 


1925~\  WHEAT  ROSETTE  AND  ITS  CONTROL  277 

of  grain  in  a  50-acre  field.  It  is  not  uncommon  to  find  many  spots  or 
large  areas  in  a  field  where  practically  all  the  wheat  plants  have  been 
killed  or  are  severely  diseased.  Sometimes,  however,  the  diseased  plants 
in  such  spots  recover  to  a  considerable  extent  and  produce  some  grain, 
altho  the  heads  are  much  smaller  than  those  produced  by  rosette-free 
plants  (Fig.  2).  In  this  case,  however,  ripening  is  delayed  and  the 
plants  are  green  when  the  normal  crop  is  harvested.  The  grain  from 
such  green  plants  shrivels  badly  and  much  of  it  is  lost  in  threshing. 
When  much  of  a  field  is  affected  by  the  disease  and  there  has  been 
considerable  recovery,  the  greatest  quantity  of  grain  is  saved  by  delaying 
harvest  until  the  diseased  areas  are  ripe.  In  some  cases,  it  is  best  to 
harvest  the  healthy  and  diseased  areas  separately,  thus  reducing  losses 
to  the  minimum. 

CROPS  AFFECTED 

Investigations  carried  on  thus  far  have  not  shown  any  other  crop 
than  winter  wheat  to  be  affected  by  the  rosette  disease.  Various  crops 
have  been  tested  for  susceptibility  to  the  disease6  and  only  a  limited 
number  of  winter  wheat  varieties  have  been  found  susceptible. 

DESCRIPTION  OF  WHEAT  ROSETTE 

During  the  first  year's  investigations,  it  was  not  possible  to  make  a 
complete  study  of  the  symptomatology  of  the  disease  owing  to  the  fact 
that  the  studies  were  not  started  until  the  trouble  had  reached  a  rather 
advanced  stage.  At  that  time,  field  spotting  was  conspicuous,  and 
diseased  plants  showed  a  characteristic  stunted  development  and  the 
production  of  an  excessively  large  number  of  secondary  tillers,  which 
gave  the  plants  a  rosette  appearance.  These  were  the  field  and  plant 
symptoms  which  attracted  attention  to  the  disease  and  which  made  it 
conspicuously  different  from  other  wheat  diseases  heretofore  known  in 
this  country.  A  rotting  of  the  -underground  portions  of  tillers  was  evi- 
dent at  that  time,  but  this  condition  was  considered  a  secondary  effect 
rather  than  a  primary  cause. 

In  1920  and  each  year  since  that  time,  the  field  studies  have  been 
started  just  at  the  time  when  winter  wheat  plants  were  beginning  to 
show  signs  of  spring  development  and  before  the  underground  portions 
of  the  plants  commenced  to  rot. 

FIELD  SYMPTOMS 

Shortly  after  the  wheat  plants  start  their  spring  growth,  infested 
fields  will  develop  very  striking  areas  or  spots  where  the  diseased  plants 
do  not  develop  normally  (Fig.  1).  These  spots  vary  in  size  and  shape. 
In  some  cases,  one  diseased  plant  may  be  found  among  plants  showing 
no  signs  of  disease.  It  is  not  uncommon  to  find  spots  20  feet  in  diameter 
and  even  larger.  In  some  cases,  more  than  95  percent  of  the  area  of  a  field 


278 


BULLETIN  No.  264 


[April, 


may  show  infestation.  The  spotting  caused  by  the  disease  occurs  inde- 
pendently of  topographical  variations,  and  frequently  single  patches  are 
found  which  involve  a  poorly  drained  dead  furrow  and  adjacent  well 
drained  portions  of  land.  Usually,  the  diseased  plants  partially  recover 
by  sending  up  secondary  tillers  which  do  not  ripen  until  after  the 
healthy  plants  are  mature,  thus  causing  a  green  spotting  in  the  infested 
fields  during  the  ripening  period. 

Field  spotting  is  caused  by  several  wheat  diseases  and  therefore  it 
is  not  specific  for  the  rosette  disease.  Most  of  the  foot  rot  diseases  pro- 


Fic.  2. — THREE  POORLY  DEVELOPED  HEADS  FROM  PLANTS  OF  HARVEST 

QUEEN  PARTIALLY  RECOVERED  FROM  THE  ROSETTE  DISEASE  AND 

THREE  TYPICAL  HEALTHY  HEADS  AT  RIGHT 

duce  this  condition,  but  in  most  cases  these  can  be  distinguished  from 
rosette  by  means  of  the  plant  symptoms.  The  field  spotting  produced 
by  the  take-all  disease  caused  by  Ophiobolus  graminis  Sacc.  does  not 
develop  as  early  in  the  spring  as  the  spotting  caused  by  the  rosette 
disease. 

PLANT  SYMPTOMS 

The  first  external  indication  of  the  rosette  disease  consists  in  a 
retarding  of  the  early  spring  development  of  the  fall  tillers.  At  this 
time,  no  external  lesions  are  consistently  associated  with  the  living  tissues 
of  the  diseased  plants  (Plate  1,  B).  Lesions  produced  by  Helmintho- 
sporium  satiz-um  P.  K.  &  B.  are  sometimes  present  on  the  subcrown 


1925} 


WHEAT  ROSETTE  AND  ITS  CONTROL 


279 


internodea.  Old  lesions  also  occur  in  the  spring  on  the  sheaths  of  the 
old,  dead,  outer  leaves.  However,  as  pointed  out  later,  these  lesions  are 
slight  and  they  do  not  occur  on  a  high  percentage  of  the  rosette-diseased 
plants  at  this  time. 


FIG.  3. — DIFFERENT  DEGREES  OF  MOSAIC  MOTTLING  AS  IT  OCCURS 
ON  THE  CURRELL  VARIETY  OF  WlNTER  WHEAT; 

HEALTHY  LEAF  ON  THE  LEFT 

This  mottling  occurs  on  all  varieties  of  wheat  known  to  be 
susceptible  to  rosette  and  on  a  large  number  of  winter  varieties 
which  do  not  develop  rosette  symptoms. 


*The  term  "subcrown  internode"  is  used  to  denote  the  structure  in  the  wheat 
seedling  between  the  crown  and  the  base  of  the  coleoptile.  Under  certain  conditions  this' 
structure  becomes  elongated. 


280  BULLETIN  No.  264-  \_Apr\l, 

In  a  week  or  ten  days  after  the  first  appearance  of  the  rosette 
disease,  the  leaf  blades  of  affected  plants  tend  to  develop  a  dark,  rather 
bluish-green  color.  Close  examination  shows  that  this  bluish-green 
coloration  is  confined  largely  to  the  leaves  which  were  produced  in  the 
fall.  As  new  leaves  begin  to  develop,  it  will  be  noted  that  they  show  a 
very  decided  mottling  (Fig.  3)  which  is  typical  of  the  mosaic  diseases 
occurring  on  the  grasses.1  At  the  same  time  the  diseased  plants  produce 
numerous  secondary  tiller  buds  and  new  tillers  develop. 

When  these  spring  tillers  have  emerged,  the  basal  tissues  of  the 
fall  tillers  begin  to  manifest  a  dull  white  to  straw  color,  and  in  the 
course  of  another  week  or  ten  days  this  tissue  may  start  to  turn  brown 
and  the  whole  base  of  the  plant  may  become  rotted  (Plate  1,  C). 

The  amount  of  this  basal  rotting  seems  to  vary  considerably  in 
different  localities  and  under  different  seasonal  conditions.  In  the  vicin- 
ity of  Granite  City,  Illinois,  this  rotting  is  more  prevalent  than  it  is 
near  Valparaiso,  Indiana.  At  Madison,  Wisconsin,  the  rotting  is  delayed 
in  the  experimental  plots  when  the  spring  is  cool. 

Microscopic  examinations  of  the  bases  of  the  stunted  tillers  of 
plants  manifesting  the  early  symptoms  of  rosette  have  never  shown 
consistently  the  presence  of  a  fungus  or  any  other  known  parasite. 
However,  it  has  been  found  that  these  tissues  contain  yellowish-brown, 
necrotic  areas  located  within  the  parenchymatous  region.  These  necrotic 
areas  seem  to  resemble  those  found  in  the  stems  of  corn  plants  and 
sugar  cane  plants  affected  by  mosaic.  A  rather  large  percentage  of  the 
host  cells  in  the  tissues  of  resetted  plants  always  show  characteristic  cell 
inclusions  (Fig.  4)  which  were  described  in  a  previous  paper.10  These 
inclusions  are  also  found  in  winter  wheat  varieties  which  develop  the 
mosaic  mottling,  but  which  do  not  develop  rosette.  They  have  never 
been  found  in  wheat  plants  growing  in  soil  known  to  be  free  from  the 
disease  infestation.  This  subject  is  discussed  later. 

The  root  systems  of  plants  in  the  early  stages  of  the  rosette  disease 
do  not  consistently  show  any  external  signs  of  infection  or  any  other 
injury.  In  a  few  cases,  lesions  have  been  found  on  the  roots,  but  fully 
as  many  have  been  found  on  the  roots  of  plants  not  showing  the  rosette 
symptoms.  As  the  disease  progresses,  the  root  systems  of  affected  plants 
show  a  retarded  development  and  they  become  infected  to  some  extent 
by  various  organisms.  In  dry  situations  diseased  plants  do  not  tend  to 
send  up  secondary  spring  tillers.  Such  plants  usually  die  early,  forming 
a  drooping  tuft  of  brown,  dead  leaves  and  tillers.  When  heavy  spring 
rains  occur,  diseased  plants  may  be  washed  entirely  out  of  the  soil, 
leaving  the  ground  bare  between  healthy  plants.  In  situations  of  favor- 
able moisture  and  high  fertility,  diseased  plants  often  recover.  Altho 
the  fall  tillers  of  such  plants  gradually  die,  the  spring  tillers  may  develop 
into  short  culms  and  produce  heads.  Such  heads  are  usually  small 
and  imperfectly  filled. 


19251 


WHEAT  ROSETTE  AND  ITS  CONTROL 


281 


B 


FIG.  4. — PHOTOMICROGRAPHS  SHOWING  DIFFERENT  TYPES  OF  CELL 

INCLUSIONS  IN  ROSETTE-DISEASED  HARVEST  QUEEN  WHEAT; 

THE  CELL  INCLUSIONS  ARE  MARKED  X 

A — An  irregular-shaped  body  showing  pseudopodia-like  projections. 
It  is  very  common  to  find  the  vacuoles  surrounded  by  a  dense  ring 
as  is  here  shown. 

B — An  elongated  type  of  cell  inclusion. 

C — A  very  common  type  of  inclusion  found  in  wheat  tissue  from 
plants  affected  by  rosette  or  mosiac  leaf  mottling.  This  body  resembles 
certain  of  the  Negri  and  Guarnieri  bodies  associated  respectively  with 
rabies  and  smallpox. 


282  BULLETIN  No.  264  Upril, 

The  most  constant  external  symptoms  of  the  rosette  disease  con- 
sist of  (1)  the  arrested  spring  development;  (2)  the  excessive  tillering, 
producing  a  rosette  appearance;  (3)  the  dark  blue-green  colo'ation  of 
the  fall  leaves  during  the  spring  growing  period;  and  (4)  thi-  mosaic 
mottling  which  occurs  on  the  leaves.  On  the  basis  of  our  present 
knowledge,  the  presence  of  Helminthosporium  lesions  or  a  rocting  of 
the  basal  parts  of  wheat  plants  cannot  by  themselves  be  considered 
diagnostic  characteristics  of  the  rosette  disease. 

As  pointed  out  above,  the  field  spotting  produced  by  wheat  rosette 
occurs  earlier  in  the  spring  than  that  produced  by  the  take-all  disease, 
and  furthermore,  the  plant  symptoms  of  these  maladies  are  now  known 
to  be  distinctly  different.  Plants  affected  by  the  take-all  disease  turn 
yellow  and  die  very  soon  after  discoloration  begins.  These  plants  show 
a  brown  to  black  coloration  on  the  tiller  bases  and  roots.  This  blacken- 
ing or  brown  coloration  may  be  due  to  a  staining  of  the  tissue  by  the 
fungus  or  to  a  definite  crust  of  mycelium  known  as  a  "mycelial  plate." 
Plants  affected  by  the  take-all  disease  seldom  send  up  secondary  tillers 
or  endeavor  to  recover  after  infection.  The  take-all  disease  frequently 
causes  nearly  mature  wheat  plants  to  bleach,  producing  a  condition 
commonly  known  as  "white-heads."  This  condition  is  never  produced 
by  the  rosette  disease. 

Hessian  fly  injury  sometimes  resembles  certain  stages  of  the  rosette 
disease  (Plate  1,  D  and  E).  In  both  cases,  the  infested  plants  are 
stunted  and  some  of  the  leaves  show  a  dark,  blue-green  coloration. 
However,  the  excessive  tillering  and  the  leaf  mottling  associated  with 
the  rosette  disease  are  not  associated  with  plants  infested  with  "fly." 
The  only  time  when  Hessian  fly  infestation  is  apt  to  be  confused  with 
rosette  is  late  spring,  and  then  little  difficulty  is  likely  to  arise,  since 
plants  infested  with  fly  only  will  show  the  fly  pupae  or  larvae  and  no 
leaf  mottling.  Those  plants  which  show  both  infestations  usually  will 
show  some  signs  of  mottling. 

In  certain  particulars  the  early  stages  of  the  rosette  disease 
resemble  the  early  stages  of  the  nematode  disease  of  wheat  as  described 
by  Leukel.4  In  each  disease  there  may  be  retarded  development  of 
the  plants  in  the  spring  and  the  leaves  may  develop  a  dark  green  colora- 
tion and  become  very  broad  and  thick;  but  in  nematode-infested  plants 
there  is,  in  addition,  usually  a  marked  crinkling  of  the  leaves  and  stems, 
a  condition  not  associated  with  the  rosette  disease.  Also,  the  leaf  and 
stem  tissues  of  nematode  infested  plants  are  very  succulent  in  nature, 
and  show  a  characteristic  sparkling  surface.  None  of  these  characters 
is  associated  with  the  rosette  disease. 

In  reviewing  the  literature  dealing  with  certain  of  the  more  obscure 
tropical  diseases  of  the  cultivated  grass  crops,  it  was  found  that  several 
of  these  possess  certain  characteristics  strikingly  similar  to  the  rosette 
disease  of  wheat.  Excessive  tillering  and  dwarfing  are  associated  with 


Rosette  Disease  of  Wheat 
Illinois  Ayr.  KXJI.  Stntinii 


PLATE  I 


PLANTS  OF  WINTER  WHEAT  SHOWING  THE  EFFECTS  OF  ATTACKS  OF  THE  ROSETTE 
AND  THE  HESSIAN  FLY,  RESPECTIVELY,  COMPARED  WITH  HEALTHY  PLANTS. 

1,  Healthy  plant  in  the  spring;  H  and  C,  plants  of  the  .tame  uge  as  A,  showing  early  ami 
advanced  stages,  respectively,  of  the  rosette;  i>,  healthy  plant  as  it  appears  in  the  late 
autumn  ;  /•',  plant  of  the  same  age  as  /',  infested  by  the  Hessian  tly.  Note  the  similarities 
in  color  but  the  differences  in  the  extent  of  tillering  in  plants  allVrted  liy  the  two  maladies 
compared  with  the  corresponding  healthy  plants. (From  Bui.  1137,  U.S.  Dept.  Agriculture.) 


THE  LIBRARY 
OF  THE 

Ur.4-  '•.••»* 


1925]  WHEAT  ROSETTE  AND  ITS  CONTROL  283 

the  Fiji,  Sereh,  and  mosaic  diseases  of  sugar  cane.5  The  leaf  mottling 
symptom  associated  with  rosette  is  strikingly  similar  to  the  mottling 
associated  with  the  mosaic  disease  of  corn,  cane,  and  other  grasses.1 

CAUSE  OF  THE  DISEASE 

Altho  a  number  of  theories  have  been  advanced  concerning  the 
cause  of 'the  rosette  disease,  the  exact  cause  is  still  undetermined.  The 
fact  that  the  disease  does  not  readily  develop  in  wheat  grown  under 
artificial  conditions  makes  it  difficult  to  conduct  many  of  the  experi- 
ments necessary  to  demonstrate  the  causal  nature  of  the  malady. 

PREVIOUS  STUDIES 

When  the  disease  was  first  discovered,  many  farmers  thought  that 
it  was  caused  directly  by  abnormal  winter  conditions.  The  disease  was 
also  thought  to  be  due  to  unfavorable  soil  type  or  unbalanced  nutrition. 
However,  subsequent  observations  have  shown  that  the  disease  occurs 
with  equal  severity  year  after  year  on  the  same  soil  regardless  of  the 
severity  of  the  winter.  As  shown  previously,6  rosette  occurs  on  many 
different  types  of  soils  and  under  many  different  topographical  condi- 
tions. It  has  also  been  found6  that  the  disease  is  not  essentially  reduced 
or  increased  in  severity  when  various  fertilizers  and  soil  correctives  are 
applied  to  the  infested  soil.  On  the  other  hand,  the  disease6  is  prevented 
when  the  infested  soil  is  disinfected  with  steam  or  with  an  .8-percent 
solution  of  formaldehyde. 

These  observations  and  results  show  that  the  causal  agent  is  soil 
borne  and  indicate  that  the  disease  is  of  an  infectious  nature.  When 
these  studies  were  started,  several  investigators  thought  that  the  disease 
was  caused  by  a  severe  infestation  of  Hessian  fly.  Careful  observations 
did  show  some  of  the  plants  to  be  infested  with  the  pupae  of  this  insect, 
but  by  far  the  largest  percentage  of  them  were  free  from  such  infesta- 
tion. Detailed  studies  on  this  phase  of  the  problem  conducted  co- 
operatively by  the  Bureaus  of  Plant  Industry  and  Entomology,  U.  S.  De- 
partment of  Agriculture,9  show  that  Hessian  fly  is  not  the  cause  of  the 
rosette  disease.  In  fact  these  studies  indicate  that  the  disease  is  not 
caused  directly  by  any  insect. 

STUDIES  ON  Helminthosporium  sativum 

Several  fungi  have  been  found  associated  with  the  rosette  disease, 
but  none  of  them  has  been  found  to  occur  on  all  resetted  plants  in  the 
early  spring  when  the  first  symptoms  of  the  disease  appear.  Helmin- 
thosporium sativum  has  been  found  more  prevalent  than  other  fungi  on 
the  diseased  plants. 

In  order  to  determine  the  possible  relationship  between  H.  sativum 
and  the  rosette  disease,  many  observations  and  experiments  have  been 
conducted.  It  was  pointed  out  in  a  previous  paper"  that  certain  inter- 


284  BULLETIN  No.  264  [April, 

esting  correlations  had  been  observed  between  the  occurrence  of  H. 
sativum  and  the  amount  of  rosette  disease  in  experimental  plots  at 
Granite  City,  Illinois.  However,  a  continuation  of  these  and  other  ob- 
servations at  Granite  City  and  elsewhere  has  not  revealed  a  constant 
correlation  between  this  parasite  and  the  disease  in  question.  Data  have 
already  been  published7  which  show  that  H.  sativum  causes  a  mild  in- 
fection on  winter  wheat  plants  in  the  autumn,  but  the  percentage  of 
infected  plants  is  much  less  than  the  percentage  of  rosette-diseased 
plants  which  develop  in  the  same  plots  the  following  spring.  This  re- 
lationship is  rather  significant  when  it  is  considered  that  the  fall  Helmin- 
thosporium  infection  is  seldom  severe  enough  to  penetrate  deeper  than 
the  first  two  or  three  leaf  sheaths,  and  it  seldom  causes  any  vital  injury 
to  the  leaves.  Furthermore,  it  has  been  shown  by  one  of  the  present 
writers7  that  the  Helminthosporium  disease  does  not  develop  to  any 
extent  at  very  low  temperatures  and  it  has  been  found  that  the  rosette 
disease  occurs  in  the  spring  before  the  Helminthosporium  fungus 
renews  its  activity. 

In  order  to  obtain  further  evidence  on  this  relationship,  inoculation 
experiments  have  been  carried  out  to  determine  if  pure  cultures  of 
Helminthosporium  sativum  will  cause  the  rosette  disease.  Numerous 
experiments  have  been  conducted  in  the  greenhouse  and  it  has  been 
found,  as  others  have  also  found,  that  H.  sativum  is  parasitic  on  wheat. 
However,  the  rosette  disease  has  never  been  produced  in  these  experi- 
ments. It  wras  found  rather  early  in  these  investigations  that  the  rosette 
disease  occurs  only  in  wheat  plants  which  have  passed  thru  a  complete 
or  shortened  winter  period;  hence  it  was  useless  to  carry  on  infection 
experiments  out  of  season  or  under  ordinary  greenhouse  conditions. 

Early  in  the  summer  of  1921,  small  plots  of  rosette  infested  soil 
near  Granite  City,  Illinois,  were  sterilized  with  formaldehyde.  Later 
in  the  summer,  some  of  these  plots  were  inoculated  with  pure  cultures 
of  Helminthosporium  sativum  isolated  from  wheat  plants  affected  by  the 
rosette  disease,  and  the  remaining  plots  were  left  uninoculated.  In  the 
autumn  these  inoculated  and  uninoculated  sterilized  plots  were  seeded 
with  Harvest  Queen  wheat.  The  following  spring,  examinations  showed 
•that  for  some  reason  the  disinfection  had  not  been  quite  complete  and 
therefore  it  was  not  possible  to  obtain  trustworthy  data.  However,  it 
was  very  evident  that  the  introduction  of  H.  sativum  into  the  soil  had 
not  increased  the  amount  of  rosette. 

During  the  summer  of  1922,  the  Helminthosporium  inoculation 
work  was  started  at  Madison,  Wisconsin,  in  order  to  eliminate  the  possi- 
bility of  accidental  rosette  contamination  which  often  occurs  in  the 
rosette-infested  district  near  Granite  City.  An  elaborate  set  of  experi- 
ments was  carried  out,  but  owing  to  the  severe  winter  of  1923  heavy 
winterkilling  occurred  in  all  of  the  plots.  However,  a  few  wheat  plants 
escaped  winterkilling  in  all  of  the  plots  and  no  rosette  developed  among 


7925]  WHEAT  ROSETTE  AND  ITS  CONTROL  285 

plants  in  the  soil  which  had  been  inoculated  with  H.  sativum.  Rosette 
did  occur  among  the  few  surviving  plants  which  were  in  the  rosette 
infested  soil  which  had  been  shipped  from  Illinois. 

In  the  summer  of  1923,  the  inoculation  experiments  were  repeated 
at  Madison,  Wisconsin,  and  precautions  were  taken  to  prevent  winter 
injury  by  means  of  a  hay  mulch.  As  a  result,  very  little  winter  injury 
occurred  in  any  of  the  plots  and  dependable  data  were  obtained  on  the 
relationship  between  Helminthosporium  sativum  and  the  rosette  disease. 
These  experiments  are  described  and  the  results  given  as  follows: 

Methods  Employed  in  Studies 

These  studies  were  conducted  out-of-doors  in  plots  30  inches  wide 
and  36  inches  long.  Each  plot  was  surrounded  by  a  frame  constructed 
of  pine  boards  8  inches  wide.  This  frame  was  set  3  inches  into  the  soil; 
thus  5  inches  of  the  frame  served  as  a  protective  wall  surrounding  the 
plots.  Openings  were  cut  at  the  bottom  of  each  frame  to  provide  for 
surface  drainage.  The  soil  used  in  these  plots  consisted  of  sandy  loam 
field  soil  obtained  from  the  Experiment  Station  farm  at  Madison,  Wis- 
consin. This  soil  was  not  infested  with  the  rosette  causal  agent,  but  in 
order  to  safeguard  against  accidental  contamination  the  soil  was  steril- 
ized with  steam. 

Two  strains  of  Helminthosporium  sativum  were  used  in  these 
studies.  One,  designated  No.  408,  was  obtained  thru  the  kindness  of  Dr. 
F.  L.  Stevens.  This  strain  was  isolated  by  Dr.  Stevens  from  a  rosette- 
diseased  plant  grown  in  a  rosette-infested  field  near  Granite  City, 
Illinois,  and  is  the  one  which  he12  designates  Helminthosporium  No.  1. 
The  other  strain,  designated  No.  407,  was  isolated  by  one  of  the  writers 
(Webb)  from  a  rosette-diseased  plant  showing  the  late  stages  of  rotting. 

The  plots  were  inoculated  by  applying  water  suspensions  of  the 
conidia  to  the  upper  four  inches  of  the  soil  some  time  before  sowing 
the  seed  and  again  at  the  time  of  sowing  as  indicated  in  Table  2.  One 
plot  was  devoted  to  each  strain  of  the  organism.  One  plot  of  sterilized 
soil  was  left  uninoculated  to  serve  as  a  control  and  one  plot  was  devoted 
to  rosette-infested  soil  from  Granite  City  to  serve  also  as  a  control. 

In  order  to  obtain  results  from  soil  in  which  Helminthosporium 
sativum  had  become  thoroly  established,  one  of  the  plots  inoculated  the 
previous  year  (1922)  with  strain  No.  407  and  another  plot  consisting  of 
infested  Minnesota  soil  were  also  included  in  the  experiment.  The  Min- 
nesota soil  was  very  kindly  supplied  by  Mr.  J.  J.  Christensen  of  the 
Minnesota  Agricultural  Experiment  Station.  This  soil  was  inoculated  a 
number  of  years  previous  to  1923  with  a  pure  culture  of  //.  sativum 
isolated  from  diseased  spring  wheat  grown  in  Minnesota.  Mr.  Christen- 
sen2 previously  reported  that  he  had  obtained  a  rosette-like  manifesta- 
tion in  spring  wheat  grown  in  this  artificially  inoculated  soil;  conse- 
quently it  was  important  that  this  soil  should  be  included  in  the  series. 


286 


BULLETIN  No.  264 


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1925~\  WHEAT  ROSETTE  AND  ITS  CONTROL  287 

Harvest  Queen  wheat  seed  was  sown  in  each  of  the  inoculated  plots 
and  the  controls.  The  same  lot  of  seed  was  used  for  all  of  the  plots 
except  those  containing  the  Minnesota  soil  and  the  accompanying  con- 
trol. This  last  lot  of  seed  was  somewhat  lower  in  susceptibility  to  rosette 
than  the  first  lot;  however,  its  susceptibility  was  sufficiently  high  to 
serve  as  an  accurate  test  for  the  infectiousness  of  the  experimental  soil. 
In  addition  to  Harvest  Queen  seed,  one  row  of  the  Currell  variety  of 
winter  wheat  was  sown  in  the  control  plot  containing  the  rosette-infested 
soil.  This  variety  does  not  develop  the  rosette  condition,  but  it  does 
develop  a  severe  type  of  leaf  mottling  when  grown  in  rosette-infested 
soil. 

Results 

The  results  of  the  infection  studies  with  Helminthosporium  sativum 
are  given  in  Table  2.  In  all  cases  where  early  spring  (April  15)  obser- 
vations were  made,  it  was  found  that  Helminthosporium  infection  was 
much  more  prevalent  on  plants  growing  in  the'  plots  which  had  been 
inoculated  with  pure  cultures  of  H.  sativum  than  it  was  on  plants 
growing  in  the  rosette-infested  soil.  It  is  especially  significant  that  such 
a  high  percentage  of  infection  took  place  in  plants  growing  in  Plot 
5,  which  was  inoculated  with  culture  No.  408.  This  Plot  and  Plot 
4  were  purposely  inoculated  very  heavily  in  order  that  H.  sativum 
might  be  given  the  maximum  opportunity  to  produce  the  rosette  disease. 
However,  this  fungus  failed  to  produce  rosette  or  the  mosaic  leaf 
mottling. 

A  high  percentage  of  rosette  and  mosaic  leaf  mottling  (98  percent) 
developed  in  the  early  sown  rosette-infested  control  (Plot  2)  and  46 
percent  rosette  and  leaf  mottling  occurred  in  the  late  sown  rosette- 
infested  control  (Plot  7)  which  accompanied  the  Minnesota  soil. 
All  of  the  plants  grown  in  the  Helminthosporium-infested  soil,  obtained 
from  Minnesota,  were  exceedingly  robust  and  there  was  no  sign  of 
rosette  or  leaf  mottling  on  any  of  the  plants.  The  reduced  amount  of 
rosette  in  the  above  rosette-infested  control  is  assigned  to  the  lower 
susceptibility  of  the  seed  used  and  to  the  fact  that  the  seed  was  not 
sown  until  very  late  in  the  fall.  It  has  been  shown  previously6  that 
late  sowing  tends  to  reduce  the  amount  of  rosette. 

The  photographic  evidence  obtained  from  these  experiments  is 
shown  in  Figs.  5,  6,  7,  and  8.  It  is  of  interest  to  note  that  the  rosette- 
infested  soil  used  in  Plot  2  had  been  stored  in  a  warm  greenhouse  at 
Madison,  Wisconsin,  for  three  years  previous  to  using  it  in  this  experi- 
ment. During  this  three-year  period  the  soil  was  under  air-dry  condi- 
tions and  in  spite  of  this  the  percentage  of  rosette  and  leaf  mottling  was 
not  reduced. 

Altho  the  results  of  the  inoculation  experiments  are  of  a  negative 
nature,  it  seems  rather  evident  that  they  warrant  consideration  at  this 


288 


BULLETIN  No.  264 


FIG.  5. — CONTROL  PLOTS  1  AND  2  USED  IN  THE  INOCULATION  EXPERIMENTS 

WITH  Helminthosporium  sat'wum  TO  DETERMINE  WHETHER  THIS  FUNGUS 

CAUSES  THE  ROSETTE  DISEASE  IN  HARVEST  QUEEN  WHEAT 

Plot  1,  control  consisting  of  steam-sterilized  soil  obtained  from  the 
farm  of  the  Wisconsin  Agricultural  Experiment  Station  at  Madison,  Wis- 
consin. No  rosette  developed  in  this  plot. 

Plot  2,  control  consisting  of  rosette-infested  soil  obtained  in  1920  from 
a  field  near  Granite  City,  Illinois.  Typical  rosette  and  mosaic  leaf  mottling 
occurred  in  98  percent  of  the  Harvest  Queen  plants  in  the  five  rows  on 
the  left.  From  95  to  98  percent  of  the  Currell  plants  in  the  row  on  the 
extreme  right  developed  typical  leaf  mottling,  but  no  rosette  occurred  in 
this  variety.  These  results  are  in  accord  with  all  previous  experiments. 

During  the  three-year  interval  between  the  collecting  of  this  soil  and 
the  starting  of  this  experiment,  the  soil  remained  in  an  air-dry  condition 
in  a  warm  greenhouse  at  Madison,  Wisconsin.  No  loss  of  virulence  of  the 
causal  agent  under  study  occurred. 


7925] 


WHEAT  ROSETTE  AND  ITS  CONTROL 


289 


-INOCULATED  PLOTS  4  AND  5  WHICH  ACCOMPANIED  THE  CONTROLS 
SHOWN  IN  FIG.  5 

These  plots  contained  the  same  sort  of  soil  as  Plot  1,  sterilized  in  the 
same  manner.  They  were  adjacent  to  the  controls  and  subjected  to  the 
same  conditions.  Plot  3  (not  photographed)  contained  the  same  strain 
of  the  fungus  as  Plot  4  and  presented  the  same  appearance. 

Plot  4  was  heavily  inoculated  with  Helminthosporium  sativum  (cul- 
ture No.  407)  isolated  from  a  resetted  wheat  plant  in  the  late  stages  of 
the  disease.  No  rosette  or  mosaic  leaf  mottling  occurred,  and  in  spite  of 
the  Helminthosporium  infection  present,  no  marked  injury  is  noted. 

Plot  5  was  heavily  inoculated  with  Helmintkosporium  sativum  (cul- 
ture No.  408),  supplied  by  Dr.  F.  L.  Stevens  and  isolated  from  a  wheat 
plant  in  the  late  stages  of  the  rosette  disease.  No  rosette  or  mosaic  leaf 
mottling  occurred,  and  the  plants  showed  no  ill  effects  from  the  Helmin- 
thosporium infection. 

The  plants  in  Plots  4  and  5  developed  in  exactly  the  same  manner 
as  in  control  Plot  1.  A  good  crop  of  grain  was  produced  in  all  three  plots. 


290 


BULLETIN  No.  264 


[April, 


time.  Certainly  if  Helminthosporium  sativum  were  the  direct  cause  of 
the  rosette  disease  it  could  have  been  demonstrated  in  some  of  the 
experiments  cited.  Stevens11' 12  considers  that  this  parasite  causes 
rosette  (called  foot  rot  by  him);  however,  as  pointed  out  previously" 
it  is  not  clear  that  Dr.  Stevens  obtained  the  characteristic  symptoms  of 
the  rosette  disease  in  his  inoculation  experiments.  He  did  obtain  the 
typical  infection  produced  by  H.  sativum  on  seedlings,  but  this  type  of 


FIG.   7. — REPRESENTATIVE   PLANTS   OF   HARVEST   QUEEN   TAKEN   FROM 
THE  PLOTS  ILLUSTRATED  IN  FIGS.  5  AND  6 

A — Plant  from  Plot  5  inoculated  with  culture  No.  408. 

B — Plant  from  Plot  4  inoculated  with  culture  No.  407. 

C — Plant  from  Plot  1  containing  sterilized  soil  control. 

D — Resetted  plant  from  Plot  2  containing  rosette-infested  soil.  . 

injury  should  not  be  confused  with  the  rosette  disease  which  attracted 
the  attention  of  plant  pathologists  in  1919. 

It  has  been  reported2  that  Helminthosporium  sativum  produces 
dwarfing,  proliferations,  and  dark  green  foliage  on  certain  varieties  of 
spring  wheat  and  barley;  however,  all  data  available  at  present  indicate 
that  these  conditions  occur  very  irregularly  in  spring  wheat  and  barley 
and  that  they  are  not  identical  from  the  standpoint  of  cause  with  the 
similar  conditions  associated  with  the  rosette  disease. 

In  view  of  the  above  evidence,  we  feel  there  is  justification  for 
considering  that  the  rosette  disease  of  winter  wheat  is  due  to  some  other 
cause  than  Helminthosporium  sativum.  All  of  the  evidence  which  has 
been  obtained  indicates  that  wheat  rosette  is  an  infectious  disease,  and 
at  the  present  time  there  is  considerable  indication  that  the  disease  may 


1925} 


WHEAT  ROSETTE  AND  ITS  CONTROL 


291 


be  caused  by  a  virus.  All  of  the  external  symptoms  of  rosette  are  com- 
monly associated  with  the  mosaics  of  corn  and  sugar  cane,  and  the 
microscopic  symptoms  are  also  similar  to  those  associated  with  certain 
of  the  mosaic  diseases.  The  mosaic  mottling  occurs  on  a  large  number 
of  varieties  of  winter  wheat  and  it  would  not  be  surprising  to  find  a  few 


B 


FIG.  8. — TYPICAL  HARVEST  QUEEN  WHEAT  PLANTS  FROM 
STERILIZED  AND  FROM  INFESTED  SOIL 

A — From  a  plot  containing  steam  sterilized  soil. 

B — From  a  plot  containing  soil  obtained  from  the  Minnesota 
Agricultural  Experiment  Station,  which  contained  Helmin- 
thosporium  sativum.  No  rosette  or  mosaic  mottling  developed 
in  this  plot  and  the  progress  of  the  plants  was  the  same  as  that 
of  plants  grown  in  the  sterilized  control  plot. 

C — Rosette-diseased  plant  from  rosette-infested  soil.  Forty- 
six  percent  of  the  plants  in  this  plot  developed  rosette.  This 
percentage  would  have  been  higher  if  the  seed  had  been  sown 
earlier  in  the  fall.  Also,  the  particular  strain  of  Harvest  Queen 
used  in  this  plot  and  in  the  accompanying  plots  is  slightly  less 
susceptible  to  rosette  than  that  used  in  Plots  1  to  5. 


292  BULLETIN  No.  264  [April, 

varieties  which  become  stunted  and  proliferate  freely  as  is  the  case  with 
certain  varieties  of  sugar  cane  and  corn  when  infected  with  the  mosaic 
virus.  Owing  to  the  unusual  conditions  necessary  for  the  development 
of  rosette  and  the  mosaic  mottling,  it  has  not  been  possible  to  demon- 
strate the  virus  nature  of  these  troubles  by  the  usual  methods  employed 
in  the  study  of  the  mosaic  diseases.  It  is  hoped  that  studies  now  under 
way  may  throw  some  additional  light  on  this  phase  of  the  problem. 

CELL  INCLUSIONS 

Cell  inclusions  have  been  described  in  a  previous  publication10  and 
they  are  illustrated  here  in  Fig.  4.  Similar  inclusion  bodies  are  also 
associated  with  several  of  the  mosaic  diseases.  As  pointed  out  by  one 
of  the  present  writers  in  a  report,8  there  has  been  considerable  contro- 
versy regarding  the  exact  nature  of  many  of  the  cell  inclusions  asso- 
ciated with  virus  diseases.  Many  investigators  have  held  that  they  are 
definite  parasitic  organisms,  while  others  hold  that  they  are  reaction 
products  and  have  nothing  to  do  with  the  cause  of  the  disease.  Altho 
the  exact  nature  of  the  cell  inclusions  occurring  in  wheat  is  not  known, 
it  has  been  found  that  these  inclusions  have  considerable  diagnostic 
value. 

SPREAD  OF  THE  DISEASE 

As  stated  previously  in  this  paper  and  in  an  early  publication,6  the 
rosette-disease  causal  agent  is  in  the  soil  and  is  spread  by  the  move- 
ment of  the  soil.  Experiments  have  been  conducted  to  determine 
whether  the  malady  is  carried  in  the  seed  or  in  the  stubble,  but  negative 
results  were  always  obtained. 

CONTROL  MEASURES 

The  rosette  disease  of  wheat  has  been  controlled,  in  the  areas  where 
it  has  been  found,  by  the  use  of  varieties  that  are  either  immune  from, 
or  highly  resistant  to,  the  disease. 

More  than  two  hundred  varieties  and  selections  of  winter  wheat 
from  all  parts  of  the  United  States  have  been  grown  on  rosette-infested 
soil  in  Illinois  and  Indiana  during  the  past  five  years  and  the  data 
obtained  from  the  experiments  appear  in  the  literature.6- 14  Certain  of 
these  published  results,  however,  are  sufficiently  important  to  be  in- 
cluded here.  The  susceptible  varieties,  arranged  according  to  classes, 
are  presented  in  Table  3,  which  is  reproduced  from  a  previous14  publi- 
cation. The  Cereal  Investigations  (C.  I.)  accession  number,  or  other 
source  of  seed  and  head  descriptions  are  given  for  each  variety.  The 
percentage  of  plants  infected  in  each  variety  was  determined  on  the 
basis  of  macroscopic  symptoms  of  the  disease. 

Harvest  Queen  (known  as  white  chaffed  Red  Cross  and  Salzer's 
Prizetaker)  is  the  only  widely  grown  variety  that  has  proved  highly 


1925]  WHEAT  ROSETTE  AND  ITS  CONTROL  293 

susceptible.  The  varieties  "Brunswick,"  Nigger,  Penquite  (Velvet 
Chaff),  Missouri  Bluestem,  Selection  from  Indiana  Swamp,  Fultz 
(selection  by  Kentucky  Agricultural  Experiment  Station),  Miller's 
Pride,  and  Illini  Chief  are  very  susceptible.  These  highly  susceptible 
varieties  represent  about  4  percent  of  the  total  number  of  varieties  tested 
and  this  relatively  small  percentage  is  striking. 

Twelve  varieties,  aggregating  6  percent  of  the  series,  proved  slightly 
susceptible  and  an  equal  number  of  varieties  showed  slight  traces  of  the 
disease. 

Inconsistent  results  have  been  obtained  with  a  few  of  the  varieties 
at  different  places  and  during  different  years,  but,  for  the  most  part, 
results  have  been  very  uniform.  The  varieties  and  selections  resistant  to 
the  rosette  disease  have  been  listed  in  previous  publications.3- 14 

The  more  important,  hard,  red,  winter-wheat  varieties  for  central 
and  northern  Illinois  conditions  in  this  list  are  Beloglina,  Black  Hull, 
Kanred,  Malakof,  Michikoff,  P  1066,  P  1068,  and  Turkey  Red.  Among 
the  more  prominent  soft,  red  winter  wheats  that  are  resistant  to  rosette 
are  Early  Harvest,  Eversole,  Fulcaster,  Gladden,  Mammoth  Red, 
Mediterranean,  Michigan  Amber,  Red  Rock,  and  Red  Wave. 

Red  Wave,  which  appears  among  the  resistant  or  immune  varieties, 
has  largely  been  substituted  for  the  Harvest  Queen  variety,  while  Fultz, 
many  strains  of  which  are  either  immune  or  highly  resistant,  has  been 
used  to  some  extent.  A  number  of  hard,  red,  winter  wheats  of  the  Turkey 
type,  such  as  Illinois  10-110  and  Kanred,  are  immune  and  some  of  these 
have  been  sown.  The  large  number  of  varieties  which  are  not  suscep- 
tible to  rosette  makes  the  practical  control  of  this  disease  relatively 
simple,  but  the  presence  of  flag  smut  in  southern  Illinois  in  the  same 
area  with  rosette  presents  complications.  Several  varieties  are  either 
immune  or  resistant  to  flag  smut,  as  shown  by  Tisdale,  Dungan,  and 
Leighty.13  The  varieties  resistant  to  flag  smut  are  fewer  in  number  than 
those  resistant  to  rosette  and  the  varieties  which  are  resistant  to  both 
diseases  are  still  fewer  in  number. 

Of  the  many  varieties  that  have  been  grown  in  both  the  flag  smut 
and  rosette  experimental  plots,  tho.se  that  are  immune  from  rosette,  and 
either  immune  from,  or  highly  resistant  to,  flag  smut  are  Early  Harvest, 
Eversole,  Grandprize,  Illinois  10-110,  Kanred,  Mammoth  Red,  P  1066, 
P  1068,  Red  Rock,  and  Shepherd. 

The  Red  Wave  and  Fultz  varieties,  while  resistant  to  rosette,  are 
somewhat  susceptible  to  flag  smut,  and  Illinois  10-110  and  Kanred, 
while  practically  resistant  to  both  diseases,  are  not  well  adapted  to  the 
southern  Illinois  areas.  Shepherd,  however,  is  a  variety  that  seems  to 
offer  excellent  possibilities.  It  is  resistant  to  both  the  rosette  and  flag 
smut  diseases  and  has  yielded  well  in  variety  tests  on  Experimental 
plots  in  southern  Illinois.  A  resistant  selection  of  Harvest  Queen  (the 
so-called  Salzer's  Prizetaker)  has  been  developed,  and  while  this  selec- 


294 


BULLETIN  No.  264 


TABLE  3. — VARIETAL  RESISTANCE  IN  WHEAT  TO  ROSETTE  DISEASE 

Varieties  of  winter  wheat  found  susceptible  to  the  rosette  disease,  in  experiments 
conducted  in  the  crop  year  1921-22,  at  Granite  City,  Illinois,  and  at  Wanatah,  Indiana, 
grouped  according  to  classes,  with  head  characters  for  each  and  percentage  of  infection. 


Variety 

C.  I.  No.  or  source 

Head 
characters* 

Percentage  of  plants 
infected1" 

Granite 
City,  111. 

Wanatah, 
Ind. 

Hard  Red  Winter 
Pesterboden 
Budapest     

5789  

BWG 
BWG 

AWG 
BRG 

trace 
0 

0 
0 

0 
0 

0 

0 
0 

80-90 
1-2 

95-100 
95-100 
95-100 

5-10 

0 
0 
0 

75 
95-100 
95-100 
95-100 
0 

0 
0 
95-100 

1 
1-2 

0 
0 

trace 
trace 

trace 
2 
98 

1 
trace 

trace 
2 
1 
trace 

45 
0 

55 
50 

5 
25 
1  + 
3 
1  + 
trace 
trace 
trace 

20 
75 
90 

75 

1 

trace 
1-2 
40 
trace 

2 

trace 
trace 

Turkey 
Malakof 

4898  

Soft  Red  Winter 
Alabama  (Wis.  No.  81) 
Brown  Bearded  

5785  

3118  

"Brunswick"0  

Ind.  Sta  

China 
Pennsylvania 
Bluestem..  .  . 
Currell  

5342  

ARC 
ARG 

BWG 
AWG 
AWG 
AWG 

AWG 
BWG 

AWG 
AWG 
AWG 

AWG 
ARG 
ARG 
AWV 
AWV 
AWG 
BRG 
BRG 

BRG 
BRG 
BWG 
BRV 
ARG 

ARG 
ARG 
BRG 
BRG 
AWG 
(Club) 
BRG 

ARG 

3326  

Fulcaster 
Stoner  (Marvelous) 
Fultz  

3605  

5308  

Fultz  

3598  

Fultz.  ... 

1923  

Fultz  (Kentucky  Selec- 
tion)   

6896  

Gipsy 
Niagara  

5307  

Harvest  Queen 
(Control)  

Granite  City,  111.  .  . 
4882  

Harvest  Queen  

Harvest  Queen  

Kans.  Sta  

Harvest  Queen 
Kessinger  . 

Ind.  Sta.d  

Illini  Chief  

5956  

Illini  Chief  

Ind.  Sta  

Jones  Fife  
Jones  Fife  
Leap  

Ind.  Sta.  (R.  25)  .  . 
Ind.  Sta.  (R.  13)... 
5618  

Mediterranean  

3332  

Mediterranean  

3467  

Mediterranean 
Miller's  Pride  .... 
Missouri  Bluestem 
Nigger  

4865  .  . 

1912  

5366e  

Penquite  (Velvet  Chaff) 
Poo'.e  

3068  

5653  

Red  May 
Enterprise  

3399.. 

Red  Cross  

5318  

Sel.  from  Ind.  Swamp.  . 
Sel.  from  Ind.  Swamp.  . 
Selection  No.  13631  ... 

Selection  No.  131156.. 
Common  White 
Honor  

4834  

3334  

4081  

4808  

6161  

See  bottom  of  next  page  for  explanatory  notes. 


1925]  WHEAT  ROSETTE  AND  ITS  CONTROL  295 

tion  is  susceptible  to  flag  smut,  efforts  are  being  made  to  develop  a  strain 
from  it  which  will  prove  resistant  to  both  diseases. 

Altho  only  about  10  percent  of  the  winter-wheat  varieties  and  selec- 
tions grown  on  rosette-infested  soil  have  shown  definite  symptoms  of 
the  disease,  that  is,  distinct  stunting  and  excessive  proliferation,  fully 
85  percent  of  the  varieties,  which  have  heretofore  been  considered 
resistant  to  the  rosette  disease,  have  shown  a  mosaic  leaf  mottling  in 
various  degrees  of  severity.  All  varieties  which  are  susceptible  to  rosette 
are  also  susceptible  to  the  leaf  mottling.  In  general,  the  mottling  does 
not  seem  to  interfere  with  the  development  of  the  plants;  however,  in  a 
few  cases  (Malakof,  Crimean,  and  Currell)  the  mottling  is  severe  and 
it  appears  to  affect  the  normal  development  of  the  plants.  It  is  of  inter- 
est to  note  that  certain  varieties  show  a  variation  in  the  distribution  and 
severity  of  the  rosette  symptoms  for  different  years  and  it  is  of  further 
interest  to  note  that  certain  varieties  frequently  show  gradations  be- 
tween typically  resetted  and  healthy  plants. 

Other  possible  control  measures  have  been  investigated,  and,  while 
they  have  proved  effective,  they  are  not  practical  from  the  field  stand- 
point. Sterilization  of  infested  soil  with  either  steam  or  formaldehyde 
adequately  controls  the  disease.  Moreover,  the  fall  date  of  planting  in 
infested  soil  bears  a  definite  relation  to  the  disease.  Within  limits,  the 
distribution  and  severity  of  the  disease  decreases  directly  with  delayed 
planting.  No  symptoms  have  been  noted  with  Harvest  Queen  (the  most 
susceptible  variety)  when  it  was  planted  so  late  in  the  fall  that  it  did 
not  emerge  until  spring,  or  on  any  of  the  spring  varieties. 

CONCLUSIONS 

The  cause  of  wheat  rosette  is  still  unknown.  There  are  indications 
that  it  may  be  a  phase  of  a  mosaic  disease. 

The  causal  agent  is  soil  borne  and  the  disease  recurs  every  year 
when  susceptible  varieties  of  winter  wheat  are  sown  on  infested  soil. 
The  disease  has  not  been  noted  in  spring  wheat. 

Since  the  disease  occurs  in  relatively  few  varieties  it  can  be  success- 
fully controlled  by  sowing  those  which  are  resistant.  The  mosaic  leaf 
mottling  which  occurs  on  resetted  plants  and  also  independently  of 
rosette  occurs  on  a  large  number  of  varieties  when  sown  in  infested  soil. 
However,  this  leaf  mottling  does  not  seem  to  cause  a  reduction  in  crop 
yield  in  most  varieties. 


Notes  to  Table  3 : 

»A  =  awnless;  B  =  bearded;  W  =  white  chaffed;  R  =  red  chaffed;  G  =  glabrous,  or  smooth 
chaffed;  V  =  velvet  chaffed. 

bTrace  =  less  than   .5  percent;   0  =  no  disease:    —  :=  not  tested  at  that  place. 

'Received  by   the   Indiana   Agricultural    Experiment   Station    from   Brunswick,    Germany. 

"•Either  a   somewhat  resistant  strain  or  mixed   somewhat   with  some   similar   resistant   variety. 

•A  strain  descended  from  a  single  plant  selection.  Other  varieties  of  the  Fulcaster  group  to  which 
this  strain  is  similar  are  generally  immune. 


296  BULLETIN  No.  264 

LITERATURE  CITED 

1.  BRANDES,  E.  W. 

1919.  The  mosaic  disease  of  sugar  cane  and  other  grasses.    U.  S.  Dept.  Agr.  Bui. 
829,  1-25. 

2.  CHRISTENSEN,  J.  J. 

1922.  Studies  on  the  parasitism  of  Hflminthosporium  sativum.    Minn.  Agr.  Exp. 

Sta.  Tech.  Bui.  11,  1-42. 

3.  JOHNSON,  A.  G.  McKiNNEY,  H.  H.,  WF.BB,  R.  W.,  and  LEIGHTY,  C.  E. 

1924.  The  rosette  disease  and  its  control.  U.  S.  Dept.  Agr.  Farmers  Bui.  1414. 

4.  LEUKEL,  R.  W. 

1924.  Investigations  on  the  nematode  disease  of  wheat  caused  by  Tylenchus  tritici. 
Jour.  Agr.  Res.  27,  925-955. 

5.  LYON,  H.  L. 

1921.  Three  major  cane  diseases:  mosaic,  Sereh  and  Fiji  disease.    Hawaiian  Sugar 
Planters'  Assoc.    Exp.  Sta.  Bui.  Bot.  ser.  3,  pt.  1,  1-43. 

6.  MCKINNEY,  H.  H. 

1923.  Investigations  on  the  rosette  disease  of  wheat  and  its  control.     Jour.  Agr. 

Res.  23,  771-800. 


7. 


1923.  Influence  of  soil  temperature  and  moisture  on  infection  of  wheat  seedlings  by 
Helminthosporium  sativum.   Jour.  Agr.  Res.  26,  195-218. 


1925.   Certain  aspects  of  the  virus  diseases.   Phytopath.    15  (in  press). 

9.  ,  and  LARRIMER,  W.  H. 

1923.  Symptoms  of  wheat  rosette  compared  with  those  produced  by  certain  insects. 
U.  S.  Dept.  Agr.  Bui.  1137,  1-8. 

10.  ,  WEBB,  R.  W.,  and  ECKERSON,  S.  H. 

1923.  Intracellular  bodies  associated  with   the  rosette  disease  and   mosaiclike  leaf 
mottling  of  wheat.   Jour.  Agr.  Res.  26,  605-608. 

11.  STEVENS,  F.  L. 

1920.  Foot-rot  of  wheat.    Science,  n.  s.  51,  517-518. 

12.  


1922.  The  Helminthosporium  foot-rot  of  wheat,  with  observations  on  the  morphol- 

ogy of  Helminthosporium  and  on  the  occurrence  of  saltation  in  the  genus. 
111.  Dept.  Regis,  and  Educ.,  Div.  of  Nat.  Hist.  Survey  Bui.  14,  77-185. 

13.  TISDALE,  W.  H.,  DUNCAN,  G.  H.,  and  LEIGHTY,  C.  E. 

1923.  Flag  smut  of  wheat,  with  special  reference  to  varietal  resistance.    111.  Agr. 

Exp.  Sta.  Bui.  242. 

14.  WEBB,  R.  W.,  LEIGHTY,  C.  E.,  DUNCAN,  G.  H.,  and  KENDRICK,  J.  B. 

1923.  Varietal  resistance  in  winter  wheat  to  the  rosette  disease.   Jour.  Agr.  Res.  26, 
261-270. 


UNIVERSITY  OF  ILLINOIS-URBANA 


